U.S. patent number 10,283,997 [Application Number 14/967,469] was granted by the patent office on 2019-05-07 for wireless power transmission structures.
This patent grant is currently assigned to MediaTek Inc.. The grantee listed for this patent is MediaTek Inc.. Invention is credited to William Kirwin, Ron-Chi Kuo, Patrick Stanley Riehl, Anand Satyamoorthy.
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United States Patent |
10,283,997 |
Satyamoorthy , et
al. |
May 7, 2019 |
Wireless power transmission structures
Abstract
A wireless power transfer apparatus includes a support structure
having a top surface and a side surface. The support structure is
configured to support a mobile device on the top surface and a
wearable device at the side surface. The wireless power transfer
apparatus also includes a plurality of transmit coils within the
support structure. The plurality of transmit coils are configured
to wirelessly transmit power to the mobile device on the top
surface and the wearable device at the side surface.
Inventors: |
Satyamoorthy; Anand
(Somerville, MA), Riehl; Patrick Stanley (Cambridge, MA),
Kirwin; William (Acton, MA), Kuo; Ron-Chi (Tainan,
TW) |
Applicant: |
Name |
City |
State |
Country |
Type |
MediaTek Inc. |
Hsin-Chu |
N/A |
TW |
|
|
Assignee: |
MediaTek Inc. (Hsin-Chu,
TW)
|
Family
ID: |
54979485 |
Appl.
No.: |
14/967,469 |
Filed: |
December 14, 2015 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160181858 A1 |
Jun 23, 2016 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62094134 |
Dec 19, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04B
5/0037 (20130101); H02J 7/025 (20130101); H02J
5/005 (20130101); H02J 7/0042 (20130101) |
Current International
Class: |
H02J
5/00 (20160101); H04B 5/00 (20060101); H02J
7/02 (20160101); H02J 7/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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101836272 |
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Sep 2010 |
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CN |
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102570630 |
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Jul 2012 |
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CN |
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WO 2014118615 |
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Aug 2014 |
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WO |
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Other References
EP15201353.8, dated Mar. 2, 2016, European Search Report. cited by
applicant .
European Search Report dated Mar. 2, 2016 for European Patent
Application No. 15201353.8. cited by applicant.
|
Primary Examiner: Fureman; Jared
Assistant Examiner: Bukhari; Aqeel
Attorney, Agent or Firm: Wolf, Greenfield & Sacks,
P.C.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to U.S. provisional application
Ser. No. 62/094,134, titled "3D Wireless Charger," filed Dec. 19,
2014, which is hereby incorporated by reference in its entirety.
Claims
What is claimed is:
1. A wireless power transfer apparatus, comprising: a support
structure having a top surface and a side surface, the support
structure being configured to support a mobile device on the top
surface and a wearable device at the side surface; and a plurality
of transmit coils within the support structure, the plurality of
transmit coils being configured to wirelessly transmit power to the
mobile device on the top surface and the wearable device at the
side surface, wherein the plurality of transmit coils comprises a
first transmit coil that conducts current in a first direction and
a second transmit coil that conducts current in a second direction
opposite to the first direction to produce constructive
interference at the side surface; and wherein the first transmit
coil comprises a spiral-shaped winding proximate the top surface of
the support structure.
2. The wireless power transfer apparatus of claim 1, wherein the
plurality of transmit coils are connected in series.
3. The wireless power transfer apparatus of claim 1, wherein the
support structure has a central axis, and wherein the plurality of
transmit coils are configured to wirelessly transmit power to the
wearable device when the wearable device is placed on the side
surface at any angular position about the central axis.
4. The wireless power transfer apparatus of claim 1, wherein the
support structure has a height of between 2 cm and 15 cm.
5. The wireless power transfer apparatus of claim 1, wherein the
support structure has a perimeter of between 8 cm and 20 cm.
6. The wireless power transfer apparatus of claim 1, further
comprising a base housing circuitry that drives the plurality of
transmit coils, wherein the support structure extends above the
base.
7. The wireless power transfer apparatus of claim 1, further
comprising a base having a ridge to position the wearable device at
the side surface.
8. The wireless power transfer apparatus of claim 7, wherein the
base houses circuitry to drive the plurality of transmit coils and
the wireless power transfer apparatus further comprises a magnetic
shield between the plurality of transmit coils and the
circuitry.
9. A wireless power transfer apparatus, comprising: a support
structure having a cavity configured to accommodate an electronic
device; and an upper transmit coil and a lower transmit coil within
the support structure, the upper and lower transmit coils having
current that flows in opposite directions to produce magnetic
fields that constructively interfere in the cavity to wirelessly
transmit power to the electronic device, wherein the upper transmit
coil and/or the lower transmit coil surrounds the cavity.
10. The wireless power transfer apparatus of claim 9, wherein the
upper and lower transmit coils are connected in series.
11. The wireless power transfer apparatus of claim 9, wherein a
compartment of a vehicle comprises the support structure.
12. The wireless power transfer apparatus of claim 11, wherein the
compartment comprises a cup holder.
13. The wireless power transfer apparatus of claim 9, further
comprising a magnetic shield around a side of the upper and lower
transmit coils.
14. The wireless power transfer apparatus of claim 13, wherein the
magnetic shield surrounds the side of the upper and lower transmit
coils and is also formed below the lower transmit coil.
15. The wireless power transfer apparatus of claim 9, wherein the
cavity has a shape defined by an interior surface the support
structure and the support structure is configured to accommodate
the electronic device within the cavity.
16. The wireless power transfer apparatus of claim 15, wherein the
shape is a cylindrical shape.
Description
BACKGROUND
1. Technical Field
The techniques described herein relate to wireless power transfer,
and in particular to a wireless power transfer apparatus that can
wirelessly transfer power to a mobile device and a wearable device,
and to a wireless power transfer apparatus that can wirelessly
transfer power to an electronic device within a cavity.
2. Discussion of the Related Art
Wireless Power Transfer Systems (WPTS) are gaining increasing
popularity as a convenient way to deliver power without wires or
connectors. WPTS currently under development in the industry can be
separated in two major classes: magnetic induction (MI) systems and
magnetic resonance (MR) systems. Both types of systems include a
wireless power transmitter and a wireless power receiver. Such
systems can be used to power or charge mobile devices such as
smartphones or tablet computers, among other applications.
Inductive WPTS typically operate in an allocated frequency range of
several hundred kilohertz using frequency variation as a power flow
control mechanism. MR WPTS typically operate on a single resonant
frequency using input voltage regulation to regulate output power.
In typical applications, MR WPTS operate at a frequency of 6.78
MHz.
Several industry committees such as the Wireless Power Consortium
(WPC), the Power Matters Alliance (PMA), and the Alliance for
Wireless Power (A4WP) have been working on developing international
standards for consumer products based on wireless power
transfer.
WPTS have been developed that can charge multiple mobile devices at
the same time. Such devices include a charging pad that can
accommodate multiple mobile devices on the surface of the charging
pad.
SUMMARY
Some embodiments relate to a wireless power transfer apparatus. The
wireless power transfer apparatus includes a support structure
having a top surface and a side surface. The support structure is
configured to support a mobile device on the top surface and a
wearable device at the side surface. The wireless power transfer
apparatus also includes a plurality of transmit coils within the
support structure. The plurality of transmit coils are configured
to wirelessly transmit power to the mobile device on the top
surface and the wearable device at the side surface.
Some embodiments relate to a wireless power transfer apparatus. The
wireless power transfer apparatus includes a support structure
configured to accommodate an electronic device at a side surface of
the support structure. The wireless power transfer apparatus also
includes an upper transmit coil and a lower transmit coil within
the support structure. The upper and lower transmit coils have
current that flows in opposite directions and produce magnetic
fields that constructively interfere with one another at the side
surface.
Some embodiments relate to a wireless power transfer apparatus. The
wireless power transfer apparatus includes a support structure
having a cavity configured to accommodate an electronic device. The
wireless power transfer apparatus also includes an upper transmit
coil and a lower transmit coil within the support structure. The
upper and lower transmit coils have current that flows in opposite
directions and produce magnetic fields that constructively
interfere in the cavity to wirelessly transmit power to the
electronic device.
Some embodiments relate to a method of operating a wireless power
transfer apparatus. The method includes energizing the upper and
lower transmit coils with current that flows in opposite directions
to produce magnetic fields that constructively interfere with one
another at a side surface or within a cavity of a support
structure.
The foregoing summary is provided by way of illustration and is not
intended to be limiting.
BRIEF DESCRIPTION OF DRAWINGS
In the drawings, each identical or nearly identical component that
is illustrated in various figures is represented by a like
reference character. For purposes of clarity, not every component
may be labeled in every drawing. The drawings are not necessarily
drawn to scale, with emphasis instead being placed on illustrating
various aspects of the techniques and devices described herein.
FIG. 1 shows a perspective view of a wireless power transfer
apparatus that can wirelessly transmit power to both a wearable
device and a mobile device, according to some embodiments.
FIG. 2 shows a side view of the wireless power transfer apparatus
of FIG. 1.
FIG. 3 shows a more detailed view of the transmit coils, according
to some embodiments.
FIG. 4 shows a finite element analysis of the structure of FIG. 3,
and illustrates constructive interference of the magnetic fields
produced by the transmit coils at the side surface of the support
structure.
FIG. 5 illustrates a coil form with terraces and grooves that
facilitates forming the windings of the transmit coils.
FIG. 6 shows a base which may house electronics for driving the
transmit coils.
FIG. 7 shows a cover that may be placed over the coil form and the
base.
FIG. 8 shows a plot of the coupling coefficient K vs. angle when a
receiver coil is placed on the side surface at various angular
positions.
FIG. 9 shows a plot of the coupling coefficient K vs. distance when
a receiver coil is placed above the top surface at different
distances from the top surface.
FIG. 10 shows a side view of a wireless power transfer apparatus in
which power can be provided to device(s) placed in a cavity,
according to some embodiments.
FIG. 11 shows a top view of the wireless power transfer apparatus
of FIG. 10.
FIG. 12 shows a power chain for a wireless power system.
DETAILED DESCRIPTION
Wearable computing devices, such as smartwatches, for example, are
becoming increasingly popular. Wearable computing devices
(hereinafter "wearable devices") can provide a user interface that
extends the capabilities of a mobile device, and/or can monitor the
activity level and/or physiological information of a user using one
or more sensors. As with mobile devices, wearable devices are
typically powered by batteries and need to be re-charged
regularly.
Described herein is a wireless power transfer apparatus that can
accommodate both a wearable electronic device and a mobile device,
and which allows wireless power transmission to both devices
simultaneously. In some embodiments, the wireless power transfer
apparatus has a support structure sized and shaped to allow a
wearable device to be positioned at the side of the support
structure while a mobile device is placed on top of the support
structure. The support structure accommodates at least one transmit
coil shaped and positioned to transmit wireless power to both the
wearable device and the mobile device.
FIG. 1 shows a perspective view of a wireless power transfer
apparatus 10 that can wirelessly transmit power to both a wearable
device and a mobile device, according to some embodiments. Wireless
power transfer apparatus 10 has a support structure 2 that can
accommodate transmit coils 7 and 8 for transmitting power
wirelessly to device(s) positioned at a top surface 6 and a side
surface 4 of the support structure. The transmit coils include at
least one lower transmit coil 7 and at least one upper transmit
coil 8. Transmit coils 7 and 8 are schematically illustrated in
FIG. 1 and are discussed in further detail below. Support structure
2 may be formed on a base 3. In some embodiments, the support
structure 2 may have a ridge 13 to guide the wearable device 12
into a suitable position for wireless power transfer.
FIG. 2 shows a side view of wireless power transfer apparatus 10.
FIG. 2 shows a mobile device 11 may be placed on the top surface 6
of the support structure 2, and a wearable device 12 (e.g., a
smartwatch) may be placed at the side surface 4 of the support
structure 2. If wearable device 12 is a smartwatch, it may be
wrapped (at least partially) around the side surface 4 of the
support structure 2, as shown in FIG. 2. Wearable device 12 may be
positioned at any angular position around the perimeter of the
support structure 2. In operation, transmit coils 7 and 8 may be
energized to wirelessly transmit power to both mobile device 11 and
wearable device 12 simultaneously, which can provide an effective
solution for charging both a mobile device and a wearable device.
Mobile device 11 may be a battery-powered device such as a cellular
telephone, a smartphone, a tablet computer, or any other mobile
device that can be balanced on top of support structure 2 in a
position and orientation that facilitates wireless power transfer.
Wearable device 12 may be a battery-powered computing device that
may be worn by a person, such as a watch, a smartwatch, or any
other suitable type of wearable device such as a fitness tracking
device, a wireless headset, smart glasses, etc.
In some embodiments, support structure 2 and base 3 may be formed
of a rigid plastic material. However, the techniques described
herein are not limited as to the material(s) forming support
structure 2 and base 3.
In some embodiments, and as shown in FIGS. 1 and 2, the cross
section of the support structure 2 may be ellipsoidal, such as
circular, for example. However, the cross section of the support
structure 2 need not be ellipsoidal, and in some cases may be
square or rectangular, or have another suitable cross section. In
some embodiments, and as shown in FIGS. 1 and 2, the support
structure 2 may be tapered such that it has a smaller width at the
top 6 than at the base 3. Tapering the support structure in this
manner allows the side surface 4 to be angled toward the center of
the wireless power transfer apparatus 10, which can facilitate
resting a high aspect ratio wearable device, such as a smartwatch,
at the side surface 4, which can prevent the wearable device 12
from tipping over. However, the techniques described herein are not
limited in this respect, as in some embodiments the side surface 4
may be vertical or may be tapered in the opposite direction. In
some embodiments, the top surface 6 of the support structure 2 may
be flat. However, the top surface 6 need not be flat, and may have
another shape suitable for supporting a mobile device 11.
In some embodiments, the support structure 2 may have a height H
above the base 3 of between 2 cm and 15 cm. Such dimensions may be
suitable for accommodating a wearable device 12 between the base 3
and mobile device 11. In some embodiments, the perimeter P of the
support structure 2 (e.g., at the base 3) may be between 8 cm and
20 cm. Such a perimeter may allow the wearable device 12 such as a
smartwatch to be at least partially wrapped around the support
structure 2.
In some embodiments, and as illustrated in FIG. 2, the base may be
covered by magnetic shield 14 having a layer of ferrite or other
high magnetic permeability material to help shield the electronic
circuitry 16 in the base from the charging magnetic field. In some
embodiments, the magnetic shield 14 may have a relative magnetic
permeability of greater than 2, greater than 10, greater than 50 or
greater than 100, by way of example. In some embodiments,
electronic circuitry 16 includes one or more components of wireless
power transmitter 102 as discussed below in connection with FIG.
12.
FIG. 3 shows a more detailed view of transmit coils 7 and 8,
according to some embodiments. In some embodiments, transmit coils
7 and 8 may be in series with one another, and driven by the same
current. Vertical connections between the transmit coils 7 and 8
may be formed through the center of the support structure 2, as
shown in FIG. 3, to minimize asymmetry of the external magnetic
field. However, the techniques described herein are not limited to
transmit coils 7 and 8 being connected to one another, as transmit
coils 7 and 8 may be driven separately in some embodiments.
Transmit coils 7 and 8 may be driven in phase or with a phase
relationship with respect to one another.
In some embodiments, transmit coil 7 may have two turns, as
illustrated in FIG. 3. However, the techniques described herein are
not limited in this respect, as transmit coil 7 may have any number
of turns, such as one turn, two turns, three turns, or more.
In some embodiments, transmit coil 8 may include a spiral-shaped
winding near the upper surface 6 of the support structure 2 that
produces a magnetic field above the upper surface 6 to provide
power wirelessly to a device (e.g., mobile device 11) positioned on
top of the support structure 2. In some embodiments, the transmit
coil 8 may provide a uniform magnetic field over the upper surface
6 of the support structure 2.
In some embodiments, the transmit coils 7 and 8 may be wound so
that current flows in the opposite direction in transmit coil(s) 7
as compared to transmit coil(s) 8. For example, current may flow in
the counterclockwise direction in transmit coil(s) 7 and in the
clockwise direction in transmit coil(s) 8, or vice versa. Providing
current flow in opposite directions in transmit coils 7 and 8
produces constructive interference of their magnetic fields at the
side surface 4 of support structure 2 between the transmit coils 7
and 8, which can facilitate wirelessly transmitting power to
wearable device 12.
FIG. 4 shows a finite element analysis of the structure of FIG. 3,
and illustrates constructive interference of the magnetic fields
produced by transmit coils 7 and 8 at the side surface 4 of support
structure 2 between the transmit coils 7 and 8. As seen in FIG. 4,
the field is relatively uniform along a band 15 that extends around
the perimeter of the support structure 2. Accordingly, a wearable
device 12 placed at any angular location around the side surface 4
can be charged wirelessly using the magnetic field produced in this
region.
FIG. 5 illustrates a coil form with a grooved structure that
facilitates winding the transmit coils 7 and 8. Wire may be wound
around the grooves in the sides of the form, and placed in the
grooves on the top surface. The coil form may be attached to be
base, as shown in FIG. 6, by fitting the bottom flanges of the coil
form into the matching recesses in the base. In some embodiments,
the base may house electronics for driving the transmit coils 7 and
8, such as one or more inverters and control circuitry. FIG. 7
shows a cover that may be placed over the coil form and the base.
In some embodiments, the ridge 13 may be formed on the cover.
FIG. 8 shows a plot of the coupling coefficient K vs. angle when a
receiver coil is placed on the side surface 4 at various angular
positions around the side surface 4. FIG. 8 shows the coupling
coefficient K is relatively uniform, in the range of 7-9%, for
different angular positions.
FIG. 9 shows a plot of the coupling coefficient K vs. distance when
a receiver coil is placed above the top surface 6 at different
distances from the top surface 6. As shown in FIG. 9, the coupling
coefficient K starts at about 15% at a distance of 1 mm and
decreases to about 9% at a distance of 5 mm.
In view of these coupling coefficients, the apparatus may be
particularly well-suited to MR wireless power transfer, as MR
wireless power transmitters do not require a high coupling
coefficient.
Some embodiments relate to charging electronic devices placed in a
cavity. FIG. 10 shows a side view of wireless power transfer
apparatus 200 in which power can be provided to device(s) placed in
a cavity 205, according to some embodiments. FIG. 11 shows a top
view of the wireless power transfer apparatus 200. Wireless power
transfer apparatus 200 includes a support structure 202 that houses
transmit coils 207 and 208, each of which may include one or more
turns. Transmit coils 207 and 208 may have the same or similar
characteristics as wireless transmit coils 7 and 8 discussed above.
Transmit coils 207 and 208 may have current flowing in opposite
directions to produce constructive interference that concentrates
magnetic flux B in the cavity 205, which can facilitate wireless
power transfer to a mobile device 11. The magnetic flux B is
illustrated in FIG. 10. Of course, the flux directions may be
reversed depending on the direction of current flow in the transmit
coils. Optionally, transmit coil(s) 208 may include a bottom
portion 209 which may be positioned below cavity 205. Bottom
portion 209 may allow charging one or more smaller devices, such as
wearable devices, for example, which may be placed at the bottom of
the cavity 205. In some embodiments, the bottom portion 209 may be
spiral-shaped. In some embodiments, the wireless power transfer
apparatus 200 may be enclosed along the sides and/or bottom in an
optional layer of ferrite or other suitable high-permeability
material, to provide a closed path for the return magnetic flux. A
layer of high-permeability material 210 formed on the sides and
bottom of the wireless power transfer apparatus 200 is shown in
FIGS. 10 and 11. Such a layer of high magnetic permeability may be
a magnetic shield that inhibits stray magnetic fields from
extending beyond the enclosure, which may prevent stray fields from
interfering with nearby electronic circuits. The layer of high
magnetic permeability may have a relative magnetic permeability of
greater than 2, greater than 10, greater than 50 or greater than
100, in some embodiments.
Support structure 202 may have any suitable shape, such as a
cup-shape or other vessel-like shape. In some embodiments, wireless
power transfer apparatus 200 may be integrated into a cup holder or
other compartment of a vehicle.
A power chain for a wireless power system is shown in FIG. 12. The
wireless power transmitter 102 receives a fixed voltage from a DC
adapter. The fixed adapter voltage is scaled by a DC/DC converter
104 and applied to an inverter 106. However, in some embodiments,
the DC adapter output voltage may be controllable, rather than
fixed, which may allow eliminating the DC/DC converter 104. The
inverter, in conjunction with the transmitter matching network 108,
generates an AC current in the transmit coil(s) 110. The AC current
in the transmit coil(s) 110 generates an oscillating magnetic field
in accordance with Ampere's law. The oscillating magnetic field
induces an AC voltage into a tuned receiver coil 112 of a wireless
power receiver 103 in accordance with Faraday's law. The AC voltage
induced in the receiver coil 112 is applied to a rectifier 116 that
generates an unregulated DC voltage. Though shown as including
diodes, the rectifier 116 may be a synchronous rectifier, in some
embodiments. The unregulated DC voltage is regulated using a DC/DC
converter 118, which is filtered and provided to a load. In some
alternate embodiments the DC/DC converter 118 can be replaced by a
linear regulator or battery charger, or eliminated altogether.
The wireless power transmitter 102 may use a closed loop power
control scheme. The power control scheme allows individual device
power needs to be met while providing high efficiency and safe
receiver operation. The sensing and communications circuit 117 of
the wireless power receiver senses the power demands of the load by
measuring the voltage and/or current at the input of the DC/DC
converter 118. Instantaneous receiver power is fed back to the
wireless power transmitter 102 using a communication channel, shown
as the arrow labeled "Data" in FIG. 12. Any suitable communication
channel may be used, and may be in accordance with wireless
communication standards such as Bluetooth or Near Field
Communication (NFC), or by modulating the receiver coil 112, by way
of example and not limitation. The sensing and communications
circuit 117 sends data regarding the power demands of the receiver
to the wireless power transmitter 102. A detection and control
circuit 115 of the wireless power transmitter 102 detects the
signal from the wireless power receiver 103 and adjusts the output
voltage of the DC/DC converter 104 in order to satisfy the power
requirements of the wireless power receiver 103.
Various aspects of the apparatus and techniques described herein
may be used alone, in combination, or in a variety of arrangements
not specifically discussed in the embodiments described in the
foregoing description and is therefore not limited in its
application to the details and arrangement of components set forth
in the foregoing description or illustrated in the drawings. For
example, aspects described in one embodiment may be combined in any
manner with aspects described in other embodiments.
Use of ordinal terms such as "first," "second," "third," etc., in
the claims to modify a claim element does not by itself connote any
priority, precedence, or order of one claim element over another or
the temporal order in which acts of a method are performed, but are
used merely as labels to distinguish one claim element having a
certain name from another element having a same name (but for use
of the ordinal term) to distinguish the claim elements.
Also, the phraseology and terminology used herein is for the
purpose of description and should not be regarded as limiting. The
use of "including," "comprising," or "having," "containing,"
"involving," and variations thereof herein, is meant to encompass
the items listed thereafter and equivalents thereof as well as
additional items.
* * * * *